# -*- coding: UTF-8 -*-
"""
@Filename:exerc5.py
@author:Cora
@time:2025-03-07
"""

def factorial(n):
    if n == 0:
        return 1
    else:
        return factorial(n - 1) * n
n = int(input("请输入一个数字："))
print(factorial(n))
